Ren矇 Descartes (March 31, 1596 - February 11, 1650) was a French mathematician, philosopher and physiologist. Living on his modest inherited wealth, Descartes traveled, studied, wrote, and served as a soldier in Holland, Bohemia and Hungary. He created analytical geometry, which translates geometrical problems into algebraic form so that algebraic methods can be applied to their solution. Conversely he applied geometry to algebra. He propounded Cartesian dualism, stating that mind and matter are two distinct substances which can interact. He believed that god is the prime mover of matter, and that everything has a cause. Descartes died in 1650, at the age of 53, soon after becoming tutor to queen Christina of Sweden. The cause of death was said to be pneumonia.